from The American Heritage® Dictionary of the English Language, 4th Edition

n. A child's game in which each of four players stands in one of four boxes drawn on the ground in a two-by-two grid and must bounce a ball into another player's box without holding the ball or stepping out of bounds.

from Wiktionary, Creative Commons Attribution/Share-Alike License

adj. Having four equal sides; square.

adj. Solid, robust.

adj. Pertaining to a four-square cipher.

adj. A boxy style of domestic architecture with four rooms to a floor, one of which is usually a stair hall.

adj. Pertaining to the International Church of the Foursquare Gospel.

n. Alternative form of four square.

n. a four-square cipher

from the GNU version of the Collaborative International Dictionary of English

adj. Having four sides and four equal angles.

from The Century Dictionary and Cyclopedia

Having four sides and four angles equal; quadrangular: as, a foursquare altar.

That, combined with its ease of us by both consumers and businesses, make foursquare is allowing for phenomenal growth following tremendous success at South By South West. foursquare has set a goal of 1 million users by April 16, which is Foursquare Day.

Harvard natives and visitors will be able to explore the historic expanse of with greater ease as a result of a partnership with a mobile social networking application called foursquare, the University announced on Tuesday. the first location-based social networking tool to be implemented at Harvard venues in cities around the world.